It is proposed to employ a newly designed carbonate ion selective membrane electrode for the measurement and determination of carbonate in such body fluids as serum and plasma. The electrode will be evaluated for this purpose in terms of response range, selectivity, and dynamic response. Comparison studies will be carried out where the performance of the carbonate electrode will be critically tested with respect to classical analysis methods for CO2 content. BIBLIOGRAPHIC REFERENCE: H. B. Herman, G. A. Rechnitz, "Serum CO2 Determination using a Carbonate Ion Selective Membrane Electrode", Anal. Letters, 8 (3), 147 (1975).